Emergency brake control mechanism



INVENTOR WRFREEMAN TTORNEY Jan. 20, 1942. w. R. FREEMAN EMERGENCY BRAKE CONTROL MECHANISM Filed June 19, 1941 UNiTED STATES Pn'rrzrrrl r 2,270,431 EMERGENCY BRAKE CONTROL MEGHANISM Walter R. Freeman, Clayton, Mo., assigner to Wagner Electric Corporation, St. Louis, Mo., a corporation of Delaware Application .lune 19, 1941, Serial No. 398,701

(Cl. 18S-170) 9 Claims.

My invention relates to brakes and more particularly to control means for an emergency brake.

One of the objects of my invention is to provide control means for a brake of a Vehicle which right hand end of the chamber, conduit will be in direct communication with conduit t, thus placing the fluid motor incommunicatlon with the air tank. When element' li is moved to the left hand end of the chamber l0, conduit 5 will will cause said brake to be automatically applied 5 be disconnected from conduit 6 and the latter under certain conditions. will be placed in communication with an atmos- A more specific object of my invention is to plieric port l2, thereby permitting any fluid presprovide control means for an emergency brake sure in motor 'l to be exhausted to atmosphere. which is so associated with a fluid pressure 10 Associated with port l2 is a needle valve I3 for actuating system that said emergency brake will regulating the rate of now of fluid under presbe automatically applied and s0 maintained sure through port l2- when the iiuid pressure in the actuating system The fluid mOtOr 'i iS employed to control the reaches a value below a predetermined pressure. appiieatiOrl and release 0f au emergency brake Another object, is to provide mean-S for assoi4 on the motor vehicle, said brake being preferciation with a fluid pressure-actuated system on ably associated with the usual prepeiier Shaft a vehicle which Will automatically bring said i5. This brake comprises a drum i6 Secured to vehicle to a stop whenever the source of fluid `the shaft, and a brake band il anchored at i8 pressure drops below avalue whichis considered t0 a SuppOrt i9- The Support has piVOtally insufficient; for efficient and proper operation 2o mounted thereon a lever 20 connected on op- Of the fluid pressure actuated System, DOSlte Sides 0f its pvot t0 the ends Of the band Still another object is to associate with the by adl'uStable rOdS 2| and 22. The outer end automatically-operated emergency brake control of the lever is connected by a piStOIl lOd 23 t0 means, manual control means for causing the lUiStOIl 24 in cylinder 25 of the fluid motor l. brake to be held applied at will. 25 A' strong spring 26 is interposed between the Other objects of my invention will become DiStOrl and the end 2i 0f the Cylinder The a1'- apparent from the following description taken rangement iS Such that Spring 26 applies thev in connection with the accompanying drawings brake band l1 to the drum when there is no inwhich the single figure is a schematic view of fiud pleSSure acting 011 Piston 24- When fluid a brake control means embodying my invention. 30 pressure acts on said piston, Spring 26 will be Referring to the drawings in detail, the compressed and the brake band released from numeral I indicates an air pressure tank on a the drum. vehicle which receives compressed air through The means fOr controlling valve element Il of the conduit 2 from a suitable source, such as a valve 8 is a solenoid 28, the plunger '29 of which compressor (not shown). Leading from this is connected to actuate a pivoted lever 30, said tank is a conduit 3 which is connected to conieVer being COlrleCted by a DiStOrl rod 3| to Valve duit 4 for conveying air under pressure to any element Il. When the solenoid is energized, the uid pressure-actuated system such, for1 ex.. lever will be moved to the position shown in the ample, as an air pressure-actuated service brakgule, thereby Causing the valve element to be ing system of a motor vehicle (not shown), said 40 in a position where the fluid motor l wi11 be braking system comprising the usual control connected to the atmosphere. VThis will permit valve and conduits leading to brake actuating Spring 26 t0 apply the brakes. When the solenoid fluid motors. is deenergized, spring 32 associated with the A branch conduit 5 is also connected to conieVer mOVeS element Il t0 the position where duit 3 for placing said conduit and the tank in 45' conduit 5 will be in communication with concommunication with conduit 6 leading to a fluid duit 6 to permit liuid uuder'vpressure from the motor 1. Interposed between conduits 5 and 6 tank to enter the fluid motor 1 and move pistou for controlling admissionof iluid under pressure 24 thereof t0 a DOSitiOn Where brake band Il from the tank to fluid motor 'l and exhausting Will be disengaged. it from said motor, is a valve 8. This valve eom- The circuit for controlling solenoid 28 comprises a casing v9 having a cylindrical chamber Prises a grOuIlded battery 33 COHIleCted by a con- I-IJ in which is reciprocable a spool-type valve duCtOr 34 to one end of the winding of the soleelement Il. The port connections between 110m- This Conductor may have interposed chamber l0 and conduits 5 andf are so arranged therein a manual switch 35 which, if desired, can that when the valve element" is moved to the be the ignition switch for4 the engine of the motor vehicle. The other end of the winding of the solenoid is connected by a conductor 36 to one terminal 31 of a uid pressure-controlled switch 38, the other terminal 39 of said switch being connected to ground by a conductor 40.

'I'he iluid pressure-controlled switch comprises a two-part casing 4I having interposed between its parts a diaphragm 42. This diaphragm carries a plunger 43 of' conducting material, and a. spring 44 biases the plunger to a position where the plunger engages the terminal 31. Since spring 44 abuts the other terminal 39, the switch is closed when the plunger is engaged with terminal 31. The chamber 45 below the diaphragm is in communication with the pressure tank I by a conduit 46 connected to conduit 3. Thus when the pressure in the tank is of sufficient value to overcome the action of spring 44 and move the diaphragm upwardly, the switch will be opened. If the fluid pressure falls below a value suicient to compress the spring, the switch will be held closed by the spring.

The spring 44 is so calibrated that the switch will be closed Jwhenever the pressure in the tank falls below a value which is insufficient to result in proper and eillcient operation of the iluid pressure-actuated system connected to the branch conduit 4 previously referred to. When such condition arises and provided the manual switch 35 is closed, solenoid 28 will be energized and as a result thereof valve element II of valve 8 will be so positioned that uid motor 1 will be connected to the atmosphere. When this occurs, spring 26 is effective to apply band I1 of the emergency brake and thus bring the Vehicle to a stop if not already in stopped condition. If the vehicle is stopped, the brake will be applied and the vehicle will be prevented from moving. By adjustment of needle valve I3, the rate of application of the brake can be made slow or fast as desired. Thus it is seen that the emergency brake will always be applied whenever the pressure in the tank becomes dangerously low, that is, so lowthat the fluid pressure-actuated system cannot be properly operated. If such system is the vehicle braking system, then the operator,

is warned that there is not enough air pressure in the tank to give efficient operation of the brakes and the cause should be found and corrected. By having the manual switch 35 in the circuit, the circuit can be broken whenever the vehicle is left standing for along time Without any possibility of a drop in pressure causing energization of the solenoid and unnecessary consumption of current. The opening of switch 35 also insures release of the brake, if applied, and there is suflicient fluid pressure to accomplish the release.

When the pressure in tank I is above the predetermined value necessary to cause the pressurecontrolled switch to be opened, the solenoid `will be deenergized and spring 32 will move valve element I I of valve 8 to the right and cause the fluid motor 1 to be in direct communication with the pressure tank. Fluid under pressure can thus operate piston 24 of the fluid motor and release the brakes and maintain them in released condition as long as the fluid motor is in communication with the tank through valve 8.

Provision is also made to permit the emergency brake to be applied at will. The structure shown to. accomplish this comprises a Bowden wire 41, the ends of the sheath 48 of which are secured to fixed supports 49 and 50. as is the usual practice.

fluid motor in communication with the atmosphere thereby exhausting the cylinder of the fluid motor and permitting the spring to apply the emergency brake and hold it applied.

Being aware of the possibility of modifications in the particular structure herein described without departing from the fundamental principles of my invention, I do not intend that its scope be limited except as set forth by the appended claims.

Having fully described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination with a fluid pressure-actuated system provided with a stored source of uid pressure, a brake, spring means for applying said brake, means operable by fluid pressure from the source of pressure for maintaining said brake disengaged, and means controlled by iluid pressure from the source for preventing pressure from the. source from maintaining the brake disengaged and permitting engagement of the brake by the spring means when the pressure of the source drops below a predetermined value.

2. In combination with the fluid pressure-actuated system provided with a stored source of uid pressure, a brake, spring means for applying said brake, means operable by uid pressure from the source of pressure for maintaining said brake disengaged, means controlled by iluid pressure from the source for preventing pressure from the source from maintaining the brake disengaged and permitting engagement of the brake by the spring means when the pressure drops below a predetermined value, and manually-controlled means for permitting said brake to be engaged by the spring means notwithstanding the pressure source does not drop below said predetermined value.

3. In combination with a iluid pressure-actuated system provided with a stored source of pressure, a brake, spring means for applying said brake, means operable by fluid pressure from the source of pressure for maintaining said brake disengaged, means controlled by fluid pressure from the source for preventing pressure from the source from maintaining the brake disengaged and permitting engagement of the brake by the spring means when the pressure drops below said predetermined value, said last named means comprising a control valve, and means controlled by fluid pressure from the source for causing said control valve to place the fluid motor in communication with the source or disconnect it therefrom.

4. In combination with a fluid pressure-actuated system provided with a stored source of pressure, a brake, spring means for applying said brake, means operable by fluid pressure fromthe source of pressure for maintaining said brake disengaged, means controlled by fluid pressure from the source for preventing fluid pressure from the source from maintaining the brake disengaged and permitting engagement of the brake by the spring means when the pressure drops below said predetermined value, said last named meansv comprising a control valve and means controlled by the fluid pressure from the source for causing said control valveto place the uid motor in communication with the source or disconnect it therefrom, and manual means controllable from va remote point for placing said valve in a position where the brake will be caused to be engaged notwithstanding the pressure of the source is above the predetermined value.

5. In combination with a fluid pressure-actuated system provided with a stored source of fluid pressure, a brake, spring means for ap-v plying the brake,y a iiuid motor for disengaging the brake, means comprising a valve and conduit means for selectively placing the iiuid motor in communication with the source of fluid pressure or with the atmosphere, and means `for so controlling said valve by the fluid pressure of the source that said brake will be disengaged when the fluid pressure of the source is above a predetermined value and engaged when the fluid pressure of said source drops below said predetermined value. c

6. In combination with a fluid pressure-actuated system provided with a stored source of fluid pressure, a brake, spring means for applying the brake, a fluid motor for disengaging the brake, means comprising a valve and conduit means for selectively placing the fluid motor in communication with the source of fluid pressure or with the atmosphere, means for so controlling said valve by the uid pressure of the source that said brake will be disengaged when the fluid 4pressure of the source is above a predetermined value and engaged when the fluid pressure of said source drops belowsaid predetermined value, said last named means comprising a fluid motor connected to the source of uid pressure, and spring means for biasing the movable element of the uid motor to one position whenever the fluid pressure in the motor is insuiicient to compress the spring by moving the movable element to another position.

7. In combination with a fluid .pressure-actuated system provided with a stored source of fluid pressure, a brake, spring means for. applying the brake, a fluid motor for disengaging the brake, means comprising a valve and conduit means for selectively placing the uid motor in communication with the source of uid pressure fluid under pressure, a brake, spring means for or with atmosphere, a solenoid for controlling said valve, an electrical circuit for the-solenoid including a switch in said circuit, and means controlled by uid pressure from the source for maintaining said switch cpenwhen the pressure is above a predetermined value.

8. In combination with a fluid pressure-actuated system provided with a stored source of applying the brake, a iiuid motor for disengaging the brake, means comprising vvalve means andconduit means for selectively placing the fluid motor in communication with the source of pressure and with the atmosphere, spring means for normally biasing the valve mea-ns to a position where the motor is connected to the source, a

rsolenoid connected to the valvemeans for causing it to assume a position placing the motor in communication with the atmosphere when said solenoid is energized, an electrical circuit for the solenoid comprising a switch, means for biasing the switch to closed position, and a fluid motor connected to the source for lmaintaining the switch open when the pressure of the source is above a predetermined value.

9. In combination with a fluid pressure-actuated system provided with a stored source of fluidunder pressure, a brakefspring means for applying the brake, a uid motor for disengaging the brake, means comprising valve means and conduit means for selectively placing the fluid motor in communication with the source of pressure and with the atmosphere, spring means for normally biasing the valve means toa position where the motor is connected to the source, a solenoid connectedto the valve means for causing it to assume a position placing the motor in communication with the atmosphere when said solenoid is energized, an electrical circuit for the solenoid comprising a switch, means for biasing the switch to closed position, a uid motor connected to the source for maintaining the switch open when the pressure of the source is above a predetermined value, and manual means operable from a remote point for placing said valve means in a position where the motor is connected v to the atmosphere. Y

' WALTER R. FREEMAN. 

